Implications of FAD Electrode Reaction Kinetics for Electrocatalysis of NADH Oxidation and Development of NAD‐Dependent Enzyme Electrodes

FAD entrapped into the polyethyleneimine (PEI) matrix underwent 2e−/2H+ redox transformation, in contrast to the 1e−/1H+ reaction observed with non-stabilized FAD-modified electrodes. Under conditions of the 2e−/2H+ reaction, FAD/PEI-modified electrodes catalytically oxidized NADH starting from −100 mV vs. Ag/AgCl. These electrodes may be used for construction of NAD-dependent dehydrogenase electrodes for clinically important analytes such as glucose when coupled to the model enzyme glucose dehydrogenase. Latter allows detection of glucose starting from −100 mV within 0.05–5 mM concentration range. These results suggest the FAD stabilization by different matrices as a simple and promising approach to achieve its 2e−/2H+ redox chemistry resulting in catalysis of NADH oxidation.